What is cause of droopy eyelids?

Several causes: Developmental eye drooping is often not evident until later years. Acquired drooping eyes are frequent in: sleep deprivation, myasthenia gravis, hypothyroidism, connective tissue disorders. The medical term is ptosis. Most common non-developmental cause of ptosis at your age is probably myasthenia.

2 main causes: Some people have eyelids which don't open all of the way. This is called blepharoptosis aka ptosis. This is caused by weakening of the levator aponeurosis muscle which opens the upper eyelid. A different kind of droopy eyelids is excess upper eyelid skin aka upper eyelid hooding. The extra skin hangs down onto the upper eyelashes and can block vision. Treatable with eyelid +/- browlift surgery.

Several: Droopy eyelid can be congenital ( born with it); mechanical (age, disinsertion of the elevator muscle) ; neurological (nerve disease); muscular (myasthenia) or chemical (botox).

Couple possibilities: Most adult droopy eyelids are caused by either excessive skin/orbital fat weighing down the eyelid and/or the the muscle which helps to open the eye had slipped loose. Both of these can be repaired with a commonly-performed office or outpatient procedure.

Droopy eyelid: There are several causes of a droopy eyelid. Your best bet would be to have your eyes evaluated by a board certified facial plastic surgeon.